<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
   /* ul{
     display: flex;
     justify-content: space-between;
   }
   li{
     width: 200px;
     background-color: aquamarine;
   }
   .center{
     flex: 1;
   } */

   .box{
    /* overflow: hidden; */
    height: 30px;
   }
   .box div{
    background-color: aqua;
    width: 200px;
    height: 30px;
   }
   .left{
    float: left;
   }
   .right{
    float: right;
   }
   .center{
    margin: 0 auto;
   }
   /* .wrap {
        background: #eee;
        overflow: hidden; 
        padding: 20px;
        height: 200px;
        }
        .left {
        width: 200px;
        height: 200px;
        float: left;
        background: coral;
        }
        .right {
        width: 120px;
        height: 200px;
        float: right;
        background: lightblue;
        }
        .middle {
        margin-left: 220px;
        height: 200px;
        background: lightpink;
        margin-right: 140px;
        } */
</style>
<body>
    <!-- <div class="wrap">
        <div class="left">左侧</div>
        <div class="right">右侧</div>
        <div class="middle">中间</div>
    </div> -->
    <div class="box">
        <div class="left">1</div>
        <div class="right">3</div>
        <div class="center">2</div>
    </div>
    <!-- 特别注意：使用浮动来完成三列布局的时候，中间的元素应该在最后。 -->
</body>
</html>
<script>

</script>